The prior art teaches HVAC devices that, particularly when the air to be conditioned cools down while passing the evaporator of the refrigerant circuit, direct water condensed out of the air through a drainage system into the vehicle. In traditional systems, water that enters from the exterior into the HVAC device through, for example, the fresh air inlet, is not drained off through a drainage system. The water that penetrates the HVAC device through the fresh air inlet during, for example, car washing, accumulates within the inlet casing and can then penetrate the interior of the vehicle. The penetration of the water in the interior of the vehicle when the drainage of the water into the vehicle environment is not efficient occurs mores when the HVAC device is placed centrally in the vehicle with a fresh air inlet placed low relative to the evaporator of the refrigerant circuit.
Conducting water that penetrated the HVAC device into the interior of the vehicle can be avoided, at least partly, using HVAC devices of the generic type.
Prior art teaches an arrangement for draining water of a vehicle HVAC system comprising an air inlet channel, a blower with a blower casing, a casing of the HVAC system, and water guiding members for draining off water entering through the air inlet channel and transported in the direction of the blower into the HVAC system. The outflow opening of the additional drainage system on the bottom side of the air inlet channel, through which the water entering through the air inlet and into the air inlet channel is drainable from the casing or the air current before reaching the blower, should be avoided. In addition to having an additional drainage system provided within the HVAC device, another opening in the front of the vehicle is necessary, requiring another front seal.
EP 1 674 310 B1 describes a two-layer HVAC system comprising a blower provided with a suction channel and a double suction scroll casing, and an HVAC system casing. In the HVAC system casing, an evaporator is arranged for cooling the air the blower delivers. The condensation water condensed out of the air at the evaporator is drained off from the HVAC system casing over an outlet placed below the evaporator. Water that enters into the blower through the suction channel is also directed to the outlet for the condensation water by means of a drainage system including a drain pipe and a drain channel.
The drainage system prevents the back drawing of water that has already passed through the blower. Accordingly, the water that accumulates below the blower is directed to the drainage only after passing the blower.
EP 1 790 511 B1 discloses an arrangement for the air conditioning of a motor vehicle driver cabin including a blower that is connected to an inlet opening on the high pressure side and an outlet opening on the low pressure side, and an evaporator for the conditioning of air. The air drawn in through the inlet opening is dehumidified when flowing over the evaporator. The water condensed at the evaporator surface and the water entering through the inlet opening are drained out of the casing over an outflow arrangement. The outflow arrangement is provided with channels that extend from the high pressure side of the blower or the casing in an area below the evaporator to the low pressure side. The accumulated liquid is drained on the low pressure side over an outlet opening in the bottom of the casing.
The drainage of the water through the channels formed in the casing is based on the pressure ratio within the system. The inlet area of the first channels is disposed in line with the direction of the flow of air before the evaporator, and the inlet area of the second channels is disposed below or behind the evaporator. Accordingly, the water that enters through the inlet opening into the casing is transported through the blower and drained off through the first channels, and the condensate produced in the evaporator is drained off through the second channels. A water column in the drain of the drainage arrangement, which is unable to drain off because a low pressure is applied, reduces leakage to the environment of the vehicle.
EP 2 000 338 A1 and EP 2 062 762 A1 disclose an internal drainage arrangement where the water is led from the air inlet over the blower casing to the evaporator casing, and into the environment. The water is directed to the drainage only after having passed the blower.
The air inlet and the blower casing are connected to each other in their lower areas such that the water that has accumulated in the lower area of the air inlet is directed through an opening into the lower area of the blower casing. The lower area of the blower casing is connected to the upper area of the casing of the HVAC system. Water that has been directed through the blower casing below the blower is directed over a water draining groove established at the inner side of the blower casing and into the lower area of the casing of the HVAC system. The water is then drained off into the environment. Hence, the water to be drained enters into the evaporator casing above the evaporator. The lowest point of the air inlet must be located above the lower area of the blower casing and above the evaporator in order to ensure the water is drained off.
The air is drawn in by the blower and delivered into the casing of the HVAC system. The air is transported from the air inlet channel, through the blower casing, and to the casing of the HVAC system. The blower produces the air flow due to a pressure differential.
As a result of the existing pressure conditions, the air that enters into the casing of the HVAC system is discharged opposite the direction of water drainage through a connection established between the air inlet area having the lowest pressure and the blower casing area having the highest pressure within the HVAC system. The air is passed from the blower casing into the air inlet. The water is passed opposite the direction of flow of the air from the air inlet into the blower casing, which impedes sufficient drainage. Due to the lack of an altitude differential, no water column is established to overcome the opposing pressure differential and the HVAC only operates optimally in switched off condition.
Additionally, intense acoustic emissions can occur due to the connection between the blower casing and the evaporator, the connection being placed in the area of high pressure and very high velocity.
Furthermore, the water to be drained is passed over the evaporator so that water drops form at the evaporator surface, which can be entrained by the current of the air to be conditioned and directed into the interior of the vehicle. The arrangement of the water entry into the diffuser above the evaporator restricts the application to high HVAC devices and limits the installation possibilities.
The prior art teaches HVAC devices where the water entering through an inlet opening into the casing of the HVAC device is delivered through the blower before it is directed off to the drainage. Moreover, known systems, which due to design and pressure differences do not ensure sufficient drainage, have a great extension in height requiring special spacing requirements for the installation of the HVAC device.
It would be desirable to have an HVAC device for a vehicle that allows water to penetrate through an air inlet into the casing of the HVAC device and drain into a drainage system already present for water condensing at the evaporator, reliably drains water from the casing of the HVAC device by means of a drainage system having inlet casings placed low relative to the blower, the diffuser, and the evaporator, is cost-effective to manufacture, and requires minimal maintenance and minimal space.